2, 4-diamino-6-benzylpyrido-(2, 3-d) pyrimidines and method



3,322,765 Patented May 30, 1967 This application is acontinuation-in-part of applications Ser. No. 319,984, filed Oct. 30,1963, now abandoned, and Ser. No. 358,657, filed Apr. 9, 1964. Patentapplication Ser. No. 358,657, mentioned above, is itself acOntinuation-in-part of Ser. No. 207,798, filed July 5, 1962, and nowabandoned.

The subject of this invention is a family of 2,4-diamino-6-benzylpyrido(2,3-d)pyrimidines represented by Formula I.

I HZN N/ (I) wherein R is a methyl or hydrogen and X is selected fromthe class consisting of halogen, lower alkyl, lower alkoxy, nitro, aminoand hydrogen.

The members of the family in which R is methyl are prepared by route (a)(DH-CH2 o-ont 0% T i HQN- NH: \N

N on.-

The 7-hydroxyl group of II is then replaced by sulfhydryl and that inturn by hydrogen (through the action of Raney nickel). Alternatively,the 7-hydroxyl may be replaced by chlorine and then by hydrogen throughreductive procedures. This route is essentially that of our US. Patent2,937,284. The compounds in which R is hydrogen are prepared by themethod of our copending application No. 358,657, Oct. 26, 1964.

In U.S. Patent 2,937,284, it was shown that2,4-diamino-5,6-dialkylpyrido(2,3-d)pyrimidines were bactericides ofgreater activity than corresponding 6,7-dialky1 analogues previouslyknown.

It has now been found that the 6-benzyl compounds of Formula I share theactivity of the 5,6-dialkyl compounds but quite unexpectedly havemarkedly lower toxicity Since all the compounds of this type act mainlyas inhibitors of dihydrofolic reductases and it is known that markeddifferences in inhibitory levels are found for such enzymes of differingorigin, it is probable that the differences in toxicity are due to thecompounds of the present invention being weaker as inhibitors of themammalian re ductases.

These compounds are bases and are usually administered as salts ofnon-toxic acids such as hydrochloric, sulfuric, ethionic acid or thelike.

EXAMPLE 1 2,4-diamino-6-benzyl-7-hydr0xy-5-mezhylpyrido (2,3-d)-pyrimidine In a 2-liter flask equipped with a stirrer, thermometer inthe reaction mixture, and still head was placed 2.05 mole (257 g.) of2,4,6-triaminopyrimidine, 2.05 mole (450 g.) of ethyla-benzylacetoacetate and 1600 ml. of diphenyl ether. The flask washeated, with stirring, at 215-235 until distillation of ethanol andwater subsided. The reaction mixture was cooled to room temperature andan equal volume of hexane added. The mixture was filtered and washedwith hexane. The precipitate was slurried in one liter of water at -100,filtered while hot and washed with methanol. M.P. 300 (dec.), yield=332g. (5 8 percent); ultraviolet absorption spectra (10 mg./l., 1 cm.); pH1: maximum 321 mu; optical density, 0.480 and pH 11: maximum 327 mu;optical density, 0.305.

EXAMPLE 2 2,4 -a'iamivz0-6 -bdnzyl-7-mercapt0-5 -merhy lpyrido (2,3-d)-pyrimidine A mixture of 307 g. (1.09 mole) of 2,4-diamino6-benzyl-7-hydroxy-5-methylpyrido(2,3 d)pyrimidine and 300 g. ofphosphorus pentasulphide in 2400 ml. of pyridine was boiled under refluxfor one hour. Most of the pyridine was distilled off under reducedpressure and three liters of water was added to the residue. Thismixture was heated .to 80-90 and brought to pH 5 with hydrochloric acidwhile stirring vigorously. The mixture was filtered while hot and washedwith two liters of hot Water. The precipitate was slurried again in fiveliters of hot water, filtered and washed with hot water. Yield=432 g.This material was used in the subsequent reaction without furtherpurification.

EXAMPLE 3 2,4-a'iamin0-6-benzyI-S-methylpyrido(2,3-d) pyrimidine In atwo-liter flask equipped with a stirrer and reflux condenser was placed20 g. (0.05 mole) of the 2,4-diamino-6-benzyl-7-mercapto 5methylpyrido(2,3-d)pyrimidine prepared in Example 2, one liter of SD3Aalcohol percent ethanol plus 5 percent methanol) and ml. of 29 percentaqueous ammonia. The mixture was stirred and heated to boiling and smallamounts of No. 28 Active Raney Nickel Catalyst (Raney Catalyst Co.,Inc., Chattanooga, Tenn, U.S.A.) were added at twenty minute intervals.The reaction was followed by the ultraviolet absorbance of aliquots ofthe reaction mixture dissolved in 0.1 N hydrochloric acid. The reactionwas considered to be complete when the ratio of optical densities 322 m395 mg was greater than three. The reaction mixture was then filteredthrough a bed of mixed charcoal and SuperCel, washed with hot ethanoland the filtrate concentrated in vacuo to 200 ml. The precipitate whichformed on cooling and standing was filtered anddried. Yield=44.5 g. Theyield (42.5 g.) of ten such runs and 14 g. from other runs were combined(56.5 g. total) and purified by dissolving in four liters of 70 percentSD3A alcohol-30 percent water made acid to pH 3-4 by hydrochloric acid.This solution was filtered through a charcoal-Super-Cel bed andconcentrated in vacuo on a steam bath until a haze appeared. It waschilled and the precipitate filtered and dried. Yield=43 g. Ultravioletabsorption spectra (10 mg./l., 1 cm.) pH 1: maxima 232 mu (opticaldensity, 1.26); 322 mp (O.D., 0.29) shoulders at 270 m (O.D., 0.25); 330mu (O.D., 0.27). pH 11: maxima 238 mu (O.D., 1.08); 270 mp. (O.D.,0.39); 347 mu (O.D., 0.24).

3 EXAMPLE 4 2,4-diamina-7 -hydr xy-5-mezl1yl-6-( p-methylbenzyl pyrido-(2,3-d) pyrimidine Using the procedure described in Example 1,2,4-diamino 7 hydroxy 5 methyl-6-(p-methylbenzyl)pyrido(2,3-d)pyrimidine was prepared from 133.3 g. (0.570 mole) of ethylu-(p-methylbenzyl)acetoacetate and 71.2 g. (0.570 mole) of2,4,6-triaminopyrirnidine in 400 ml. of diphenyl ether. Yield=93.8 g.(56 percent). Ultraviolet absorption spectrum pH 1: maxima 220 m 320 mn;O.D. ratio 220 ru 320 m 1:0.53.

EXAMPLE 5 2,4-diamin0-7-chl0r0-5-methyl-6- (p-methylbenzylpyrid0-(2,3-d) pyrimidine In a one-liter flask fitted with a stirrer andreflux condenser was placed 29.53 g. (0.10 mole) of 2,4-diamino-7-hydroxy 5 methyl-6-(p-methylbenzyl)pyrido(2,3-d) pyrimidine, 73.0 g.(1.0 mole) of N,N-dimethylformamide and 200 ml. of chloroform. Themixture was stirred and 119 g. (1.0 mole) of thionyl chloride was addedslowly. It was then boiled for three hours, solution occurring afterone-half hour. This solution was concentrated in vacuo to a viscousliquid and cooled. Sufiicient 95 percent ethanol was added to make theliquid mobile and 29 percent aqueous ammonia was added dropwise, withvigorous stirring and keeping the temperature below 20 C., until a pHvalue of 9 was reached. This mixture was allowed to stand 18 hours at0l0 C. The mixture was then filtered and the precipitate was stirredwith 400 ml. of 2 N sodium hydroxide for three hours at roomtemperature. This mixture was filtered and washed with water to yield23.2 g. of product. This material is unstable, particularly in acidsolutions and was not further purified. Ultraviolet absorption spectrap11 1: maxirna 223 III/1., 231 mp, 359 mp; optical density ratios1:1:0.44; and pH 11: maxirna 237 m 366 m O.D. ratio 110.38.

EXAMPLE 6 2,4-diamin0-7-mercapto-5-methyl-6-(p-methylbenz) lpyrid0-(2,3-d) pyrimidine A saturated solution of ammonium hydrosulphidewas prepared by passing hydrogen sulphide gas into a cold solution of 9percent aqueous ammonia. 18.3 g. (0.058 mole) of 2,4 diamino 7chlorto-5-methyl-6-(p-methylbenZyDpyrido-(2,3-d)pyrimidine and 200 ml.of the above solution were placed in a stainless steel bomb and heatedat 130 for 6 hours. After cooling, the contents of the bomb werefiltered to yield 10.5 g. (58 percent) of crude product. This was notpurified. Ultraviolet absorption spectrum: pH 1: maximum 388 m EXAMPLE 72,4-diamino-5-methyl-6- p m elhylbenzyl pyrido (2,3 (I)- pyrimidineUsing the procedure described in Example 3, 10.5 g. of2,4-diamino-7-mercapto 5 methyl 6 (p methyl-'benzyl)pyrido(2,3-d)py-rimidine was dethiolated to yield2,4-diamino-6-(p-chlorobenzyl)-7-hydr0xy-5-methylpyrido-(2,3-d)pyrimidineUsing the procedure described in Example 1, 41.2 g. (44 percent) of thetitle compound was prepared from 75 g. (0.294 mole) of ethyla-(pchlorobenzyl)acetoacetate and 36.8 g. (0.294 mole) of2,4,6-triaminopyrimidine in 150 ml. of diphenyl ether. Ultravioletabsorption spectra (40 -ml./l., 1 cm.) pH 1: maxima 222 m (O.D. 1.38);318 nm (OD. 0.518); shoulder 297 m (O.D. 0.472); pH 11: maxima 231 nm(OD. 0.644), 286 nm (OD. 0.235), 325 my. (CD. 0.390).

EXAMPLE 9 2,4-diamin0-7-chI0r0-6-(p-chlorobenzyl) -5-mcthylpyrido(2,3-d) pyrimidine As described in Example 5, 63.14 g. (0.20 mole) of2,4 diamino 6 (pchlorobenzyl)-7-hydroxy-5-methylpyrido(2,3-d)-pyrimidine, 146 g. (2.0mole) of N,N-dimethylformamide, 400 ml. of chloroform and 238 g. (2.0mole) of thionyl chloride were mixed and boiled 5 hours. The solutionwas concentrated in vacuo at 50 and poured into 400 ml. of chilledpercent ethanol. This solution was treated with aqueous ammonia as inExample 5 and allowed to stand at 0 C. for five days. The mixture wasfiltered, washed with one liter of 50 percent ethanol, and dried to give96.0 g. of solid material which was thiolated without furtherpurification. Ultraviolet absorption spectra: pH 1: 221 m 332 m (O.D.ratio 1:0.35); pH 11: 357 mp.

EXAMPLE l0 2 ,4-diamin0-6- p-ch lorobenzyl -7-mercapto-5 -melhylpyrido-(2,3-d) pyrimidine As described in Example 6, 27.0 g. of the titlecompound was obtained by thiolation of 50.0 g. of the 7- chloro compoundobtained in Example 9. Ultraviolet absorption spectra: pH 1: maximum 385m pH 11: maximum 231 m and 373 m (O.D. ratio 1:0.44).

EXAMPLE 11 2,4-diamin0-6-(p-chlorobenzyl -5-mel]1yIpyrid0(2,3"a'pyrimidine As described in Example 3, 27.0 g. of the 7-mercapto compoundof Example 10 was dethiolated with Raney nickel catalyst to yield 3.87g. of product as the hemihydrate, a yield of 12 percent from the7-hydroxy compound, M.P. 275-7 (uncorrected). Ultraviolet spectra (10mg./l., 1 cm.) pH 1: maxima 230 my. (CD. 1.07); 322 mn (O.D. 0.244); pH11: maxima 232 mn (O.D. 0.972); 344 m (CD. 0.195).

EXAMPLE 12 2,4-diamino-6-(o-chlorobenzyl)-5-melhylpyrido(2,3-d)-pyrimidine As described in Example 1, 119 g. (51 percent) of 2,4-diamino 6 (o chlorobenzyl) 7 hydroxy 5 methylpyrido(2,3-d)-pyrimidinewas prepared from 187.8 g. (0.74 mole) of ethylot-(o-chlorobenzyl)acetoacetate and 92.6 g. (0.74 mole) of2,4,6-triaminopyrimidine. 50 g. (0.158 mole) of this 7-hydroxy compoundwas thiolated as described in Example 2 to yield 52.7 g. percent) ofcrude 2,4 diamino 6 (o chlorobenzyl) 7 mercapto 5 methylpyrido(2,3d)pyrimidine. 25 g. of this crude 7-mercapto compound was dethiolated asin Example 3 to yield a product which was recrystallized from 80 percentethanol which had been acidified to pH 3 with isethionic acid. 2.30 g.(7.2 percent) of 2,4-diamino-6- (o chlorobenzyl) 5 methylpyrido(2,3d)pyrimidine isethionate salt was obtained. M.P. 208.5 (uncorrected).Ultraviolet absorption spectra (10 mg./l., 1 cm.) pH 1: maxima 231 m(O.D. 0.868); 320 my. (CD. 0.187); pH 11: maxima 238 m (CD. 0.742); 344mp (O.D.

EXAMPLE l3 2,4-diamin0-7-hydr0xy-6-(o-methoxybenzyl)-5-methylpyrido-(2,3-d)-pyrimidine As described in Example 1, 105.2 g. (49percent) of the title compound was prepared from 174.5 g. (0.70

mole) of ethyl a-(o-methoxybenzyl)acetoacetate and 87.5 g. (0.70 mole)of 2,4,6-triaminopyrimidine. Ultr-aviolet absorption spectra (30 mg./l.,1 cm.). pH 1: maxima 222 m (O.D. 0.685); 320 m (O.D. 0.330); pH 11:maxima 233 m (O.D. 0.372); 287 m (O.D. 0.182); 324 m (O.D. 0.356).

EXAMPLE 14 2,4-diamino-6-(o-methoxybenzyl)-5-methylpyrido(2,3-d)pyrimidine As described in Example 2, 51.9 g. (100 percent) of the7-mercapto compound was obtained by thiolati-on of 50 g. (0.161 mole) of2,4-diamino-7-hydroxy-6-(o-methoxybenzyl) -5-methyl-pyrido 2,3-d)pyrimidine. Ultraviolet absorption maximum at 397 m in pH 1 solution. 25g. (0.076 mole) of this 7-mercapto compound was dethiolated as describedin Example 3 to yield 4.40 g. (17 percent) of2,4-diamino-6-(o-methoxybenzyl)-5-rnethylpyrido(2,3-d)pyrimidinehydrochloride hemihydrate after recrystallization from 70 percentethanol acidified to pH 2 with hydrochloric acid. Ultraviolet absorptionspectra (10 mg./l., 1 cm.) pH 1: maxima 218 m (O.D. 0.990); 320 m (O.D.0.2.50), shoulder 255 m (O.D. 0.240); pH 11: maxima 224 m (O.D. 0.780);260 m (O.D. 0.322); 340 m (O.D. 0.187).

EXAMPLE 15 2,4-diamino-fihydroxy-ti- (p-methoxybenzyl) -5-mcthylpyrid-(2,3-d) pyrimidine As described in Example 1, 108.5 g. (53percent of the title compound was prepared from 165.6 g. (0.656 mole) ofethyl a-(p-methoxybenzyl)acetoacetate and 82.3 g. (0.656 mole) of2,4,6triaminopyrimidine in 500 ml. of diphenyl ether. Ultravioletabsorption spectra (10 mg./l., 1 cm.) pH 1: maxima 222 m (O.D. 1.175);321 m (O.D. 0.604), shoulder 295 m (O.D. 0.494); pH 11: maxirna229:!1'1 1. (O.D. 0.673); 281 m (O.D. 0.247); 327 m (O.D. 0.518).

EXAMPLE 16 2,4-diamino-6- (p-methoxybenzyl) --methylpyria'o- (2,3-d)-pyrimidine As described in Example 2, 29.5 g. (95 percent) of the7-mercapto compound was obtained by thiolation of 29.7 g. (0.096 mole)of 2,4-diamino-7-hydroxy-6-(p-methoxybenzyl)-5-methylpyrido(2,3-d)pyrimidine. Ultraviolet absorption spectra (10 mg.,/l., 1 cm.) pH 1:maxima 222 m (O.D. 0.915); 317 m (O.D. 0.272); 400' m (O.D. 0.330); pH11: maxima 230 m (O.D. 0.959); 333 m (O.D. 0.215); 372 m (O.D. 0.304).25 g. (0.076 mole) of this 7-mercapto compound was dethiolated asdescribed ide. The mixture was filtered and the precipitate wasrecrystallized from 100 mls. of 95 percent ethanol which was acidifiedwith isethionic acid to give the basic isethionate salt. M.P. 286-9(uncorr.) yield 2.04 g. (14 percent). Ultraviolet absorption spectra (10mg./l., 1 cm.) pH 1: rnaxirna 222 m (O.D. 1.070); 322 m (O.D. 0.260); pH11: maxima 248 m (O.D. 0.798); 269 m (O.D. 0.410); 347 m (O.D. 0.220).

EXAMPLE 18 2,4 diamino 6 benzylpyrido(2,3 d)pyrimidine was prepared bythe method of Example 17.

EXAMPLE 19 EXAMPLE 20 2,4-diamin0-6- p-metlzoxy benzyl) pyrido (2,3-dpyrimidine As described in Example 17, the title compound was preparedfrom 6.48 g. (0.0295 mole) ofZ-(p-rnethoxybenzyl)-3-dimethylaminoacrolein, 2.92 g. (0.10295 mole) ofphosgene and 3.69 (0.0295 mole) of 2,4,6-triaminopyrimidine. It wasrecrystallized from 95 percent ethanol acidified with isethionic acid toyield 1.21 g. (12 percent in Example 3 to yield 2.82 g. (11 percent oftheory) of 2,4 diamino 6 (p met-hoxybenzyl) 5methylpyrido-(2,3-d)pyrimidine hydrochloride after recrystallizationfrom 50 percent ethanol acidified with hydrochloric acid. Ultravioletabsorption spectra (10 mg./l., 1 cm.) pH 1: maxima 232 m (O.D. 1.142);322 m (O.D. 0.245); pH 11: maxima 236 m (O.D. 1.036); 270* m (O.D.0.410); 347 m (0.193).

EXAMPLE 17 2,4-diamin0-6-(p methylbcnzyl) pyria0(2,3-d) pyrimidine 4.4g. (0.044 mole) of phosgene in 25 ml. of chloroform was added slowlywith cooling in an ice bath to a solution of 9.0 g. (0.044 mole) of3-dimethylamino-2- (p-methylbenzyl)-acrolein in 25 ml. chloroform. Thesolution was concentrated in vacuo on a steam bath until most of thechloroform was removed. 5.53 g. (0.044 mole) of2,4,6-triaminopyrirnidine and 125 ml. of absolute ethanol were added andthe mixture heated under reflux for 8 houns. 2 grams of sodium methoxidewas added and the mixture heated under reflux a further 2 hours. It wasthen cooled and filtered and the precipitate was stirred for 3 hourswith 200 ml. of 2 N sodium hydroxof theory) of the basic isethionatesalt hydrate. M.P. 280-5 (uncorr.). Ultraviolet absorption spectra (10mg./l., 1 cm.) pH 1: maxima 323 m (O.D. 0.239); pH 11: maxima 249 m(O.D. 0.682); 291 mp (O.D. 0.394); 349 m (O.D. 0.202).

EXAMPLE 21 2,4-diamin0-6-(p-nitrobenzyl) pyrido (2,3-d) pyrimidine 3.0g. (0.01 mole) of 2,4-diamino-6-benzylpyrido(2,3- d)-pyrimidinehydrochloride was dissolved in 50 ml. of concentrated sulphuric acid at0 C. and 1.0 g. (0.01 mole) of potassium nitrate was added withstirring. The solution was stirred 1.5 hours and then poured into 400ml. of ice and ethanol. This mixture was adjusted to a pH value of 3with 17 N sodium hydroxide and filtered. The precipitate wasrecrystallized from 800 ml. of 70 percent ethanol to give 2.0 g. (51percent of theory) of 2,4 diamino 6 (p nitrobenzyl)pyrido(2,3d)pyrimidine sulphate salt hydrate, M.P. 276-7. Ultraviolet absorptionspectra (10 ml./l., 1 cm.) pH 1: maxima 271 m (O.D. 4.439); 322 m (O.D.0.334); pH 11: m-axima 251 m (O.D. 0.415); 272 rn (O.D. 0.341); 347 m(O.D. 0.156).

What we claim is:

1. A compound represented by the formula I I He wherein R is selectedfrom the class consisting of hydrogen and methyl and X is selected fromthe class consisting of hydrogen, halogen, lower alkyl, lower alkoxy,nitro and amino.

2. 2,4 diamino .5 methyl 6 benzylpyrido(2,3 d)- pyrimidine.

3. 2,4 diarnino 5 methyl 6 benzylpyrido(2,3 d)- pyrimidine ethionate.

4. 2,4 diamino 6 benzy1pyrido(2,3 d)-pyrin1idine.

5. 2,4 diamino 6 benzylpyrid0(2,3 d)-pyrimidine ethionate.

6. 2,4 diamino 5 methyl 6 0 chlorobenzylpyrid0(2,3-d) pyrimidine.

8 References Cited FOREIGN PATENTS 774,095 5/1957 Great Britain. 620,3741/1963 Belgium.

ALEX MAZEL, Primary Examiner.

MARY OBRIEN, Assistant Examiner.

1. A COMPOUND REPRESENTED BY THE FORMULA